Positive Electrode and Battery

Abstract

The present disclosure relates to a positive electrode comprising a positive electrode active material layer and a positive electrode base material, wherein the positive electrode active material layer includes a positive electrode active material, the positive electrode active material includes a layered metal oxide, the ratio of nickel to the total amount of nickel and a transition metal in the layered metal oxide is 70% or more, and the positive electrode active material present near a surface of the positive electrode active material layer closer to the positive electrode base material has a crystallite diameter that is 200 Å to 500 Å greater than the positive electrode active material present near a surface of the positive electrode active material layer opposite to the positive electrode base material. According to the present disclosure, a positive electrode and a battery each of which is excellent in both endurance and efficiency are provided.

What is claimed is: 
     
         1 . A positive electrode comprising:
 a positive electrode active material layer; and   a positive electrode base material, wherein   the positive electrode active material layer includes a positive electrode active material,   the positive electrode active material includes a layered metal oxide,   a ratio of nickel to metallic elements except lithium in the layered metal oxide is 70 mol % or more, and   a part of the positive electrode active material present near a surface of the positive electrode active material layer closer to the positive electrode base material has a crystallite diameter that is 200 Å to 500 Å greater than a part of the positive electrode active material present near a surface of the positive electrode active material layer opposite to the positive electrode base material.   
     
     
         2 . The positive electrode according to  claim 1 , wherein the layered metal oxide is represented by a formula (1):
                   Li       1-a           Ni     x         Me       1-x         O   2             ­­­(1)                 where   a satisfies a relationship of -0.3≤a≤0.3,   X satisfies a relationship of 0.7≤x≤1.0, and   Me stands for at least one selected from the group consisting of Co, Mn, Al, Zr, B, Mg, Fe, Cu, Zn, Sn, Na, K, Ba, Sr, Ca, W, Mo, Nb, Ti, Si, V, Cr, and Ge.   
     
     
         3 . The positive electrode according to  claim 1 , wherein the positive electrode active material layer includes a first positive electrode active material layer and a second positive electrode active material layer, and the second positive electrode active material layer is positioned close to the positive electrode base material as compared to the first positive electrode active material layer. 
     
     
         4 . The positive electrode according to  claim 3 , wherein a thickness of the second positive electrode active material layer is defined as T2, a thickness of the first positive electrode active material layer is defined as T1, and a ratio of T1 to T2 (T1/T2) is from 0.33 to 3.0. 
     
     
         5 . A battery comprising the positive electrode according to  claim 1 .